Background: I've been a racewalker for four years, focusing on ultra distances in the last couple of years. I've recently decided to switch to running, so I'm starting almost from scratch. I recently completed my first running race, a 5k. I finished in 25:49. I think I could have gone faster (my goal was to break 24:00, and I thought that was realistic), but that's not really the point of this question. When I plug my race into the McMillan Running Calculator, the training speeds are all slower than what I've been doing. For example, McMillan suggests 200m sprints in 47.9 - 52.7. In my last 200m interval workout my speeds ranged from 38.21 to 43.24. McMillan suggest 400m speed workouts in 1:53.4 to 1:59.9 and sprint workouts in 1:45.4 to 1:53.4. In my last 400m interval workout my speeds ranged from 1:32 to 1:41. McMillan suggests tempo workouts in 8:44 to 9:07. In my last tempo workout my splits were 7:30 and 7:40; more typically I've been doing 8:00 - 8:30. My question: should I slow down and follow McMillan's advice? Is the McMillan data off because my race was not my true potential but just a bad race? Was my race disappointing because I am overtraining? How best should I use the McMillan data? I should state my goals: next 5k in four weeks, then a half marathon training program (which includes a 10k and 15k) with the goal half marathon in late October. Then I'd like to race for a while in the 5k to half marathon distance, eventually training up for a marathon. Long term goal is to qualify for Boston 2009. Thanks for any advice or insight you have!